Drilling motor



J. C. CURTIS DRILLING MOTOR Sept. 10, 1935.

Filed Dec. 14, 1933 2 Sheets-Sheet l 5 7 Y II I a IM M l. II. 1| C .M m 4 l G W M I. 1 N um I h w N l a l M m @m II [I @m J 2 I. /r L I wJm m I F wk W rm v1 m N 3. N www @w 3 m 1 PM Sept. 10, 1935. J. c. CURTIS DRILLING MOTOR I Filed Dec. 14 1935 2 Sheets-Sheet 2 JOHN C. CURTIS INVENTOR ATTORNEY Patented Sept. 10, 1935 DRILLING MOTOR John 0. Curtis, Garfield Heights, Ohio, assignor to The Cleveland Rock Drill Company, Cleveland, Ohio, a corporation of Ohio Application December 14, 1933, Serial No. 702,355

8 Claims.

This invention relates broadly to rock drill, but more particularly to fluid actuated feeding mechanism for rock drill of the drifter type.

One object of this invention is to provide a 5 feeding mechanism for rock drill wherein the vibrations imparted to the drilling motor by its piston upon the reversal of its strokes, are prevented to cause the longitudinal movement of the motor in a direction adverse to that of its 10 feeding motion.

Another object of this invention is to produce a rock drill feeding mechanism equipped with a device adapted to completely prevent the accidental escape of the pressure fluid from the actuating l5 surfaces of the feed piston, increasing thereby the eiiciency of the mechanism.

Other objects and advantages more or less ancillary to the foregoing reside in the specific construction and aggroupment of the elements 20 peculiar to this structure, as will become apparent from a more complete examination of this specificatio-n.

In the drawings which illustrate a preferred embodiment of the invention:

25 Fig. 1 is a longitudinal view partly in section of a drilling motor embodying the invention.

Fig. 2 is an enlarged end view of the drilling motor, looking in the direction of the arrows 22 in Fig. l.

30 Fig. 3 is an enlarged longitudinal sectional view of the feed piston shown within the left end portion of Fig. 1.

Fig. l is an enlarged longitudinal sectional view of the connection between the feed screw and the 35 drill.

Fig. 5 is an enlarged longitudinal sectional view of the stationary nut illustrated in the middle portion of Fig. 1.

Fig. 6 is a cross sectional view taken in a plane 40 indicated by line 6i in Fig. 5, showing the packing indicator in one position.

Fig. 7 is a view similar to Fig. 6 illustrating the packing indicator in another position.

Fig. 8 is a cross sectional view taken in a plane 45 indicated by line 88 in Fig. 1, illustrating the throttle valve in one position.

Fig. 9 is a View similar to Fig. 8, illustrating the throttle valve in another position.

Fig. 10 is a cross sectional view taken in a plane 50 indicated by line ll0 in Fig. 8.

Figs. 11 and 12 are diagrammatic views illustrating the relative position of the screw within its corresponding stationary nut.

Referring to the drawings, the rock drill shown 55 for the purpose of illustration comprises a cylinder l0, within which there is reciprocably mounted a piston adapted to deliver its blow to a cutting tool or drill steel 1 I. The lower external wall of the cylinder it is formed with a duality of longitudinally disposed guides I2 adapted for slidable engagement within corresponding guideways it formed on the upper wall of a feed tube or rock drill support it.

The feed tube it is preferably formed of a rectangular cross section, and has reciprocably mounted therein a rectangular piston it compris ing a bushing ll having mounted thereon a shouldered sleeve l8, which is adapted to receive a duality of oppositely disposed U-shaped packings I9. The bushing ll is accurately machined 15 to rotatably receive the smooth end of a screw 25, which is secured therein against longitudinal movement, by a nut 2i.

Depending from the rock drill Hi, there is a lug 22, which is properly machined to receive a bushing 23, within which the other smooth end of the screw 29 is rotatably mounted. The lug 22 is maintained against relative longitudinal movement with the screw 20, by a nut 2 secured on the end of the screw. 25

The screw 20 is formed of a relatively small pitch having a lead angle materially less than forty five degrees, the purpose of which will be explained later.

Secured within the middle portion of the feed tube M by bolts 25, there is a nut 26 through which the screw 20 is rotatably mounted. Intermediate its ends, the nut 26 is formed with an enlarged annular groove 28. Leading from the exterior of the feed tube I l into the groove 28, there is a screw threaded bore 29 adapted to receive in screw tight engagement therein a plug 30 formed with a head located in the exterior of the feed tube. The plug 30 is formed with an enlarged chamber 3 l, within which is reciprocably mounted the head 32 of-a plunger 33, which may protrude from the outer end of the plug 30 through a restricted bore 34. Interposed between the bottom of the chamber 3| and the plungers head 32, there is a compression spring 35 constantly exerting pressure on the plunger 33 for driving the latter toward the groove 28. Within the groove 28 and a portion of the threaded bore 29 there is inserted packing material such as asbestos loaded with graphite or other material best suitable for packing the screw 26 as will be explained hereafter.

Secured within the left end portion of the feed tube l 4 by means of bolts 36, there is a back head 37 formed with a valve chamber 38 having, ro-

I an.

tatably mounted therein, a throttle valve 39. The outer end of the chamber 38 is threaded to receive, in screw tight engagement therewith, a nut 46 within which is rotatably secured a tubular member 6|, to which the end of a pressure fluid conduit may be secured for admitting pressure fluid into the chamber 38. The valve 39 is provided with a centrally disposed bore 42 connected with the periphery of the valve through a passage 43. Disposed circumferentially on the valve 38 in a vertical plane passing through the passage 43, there is a groove 44 having the ends thereof maintained in spaced relation with the passage 43. This last groove is in constant communication with a vent port 45 leading to the exterior of the back head 3?. Again leading from the throttle valve chamber 38 there is an inlet port 46 opening into the front or right end portion of the feed tube M, and an inlet port 41 opening into the rear or left end portion of the feed tube.

The throttle valve 39 is formed with a tapered shank 48 extending to the exterior of the back head 3'17, and adapted to receive a cup-shaped handle 49, secured thereon by a nut 50. The external wall of the cup handle 39 is knurled as at 5!, thus providing a handle comfortable to the hand of the operator.

During the operation of the mechanism, assuming that the throttle valve 39 is located in the position illustrated in Fig. 9, pressure fluid is admitted from the throttle valve bore 42 into the rear end portion of the feed tube l4, through the passage l3, and port 47, thus exerting pressure on the piston l6, tending to move the latter forwardly or toward the right. However, the threads of the screw 2G, engaging the corresponding threads of the stationary nut 26 as shown in Fig. 12, being formed of a relatively sharp lead angle, will not respond to the pressure acting on the end of the screw to cause the rotation and longitudinal movement of the latter. The engagement of the threads of the screw with the threads of the nut, will create sufficient friction to prevent the rotation of the screw and consequently its longitudinal motion,

preventing thereby longitudinal or feeding motion to be imparted to the drilling motor ID. When it is desired to impart feeding motion to the drilling motor, the throttle valve 52 controlling the admission of the pressure fluid therein, may be positioned to admit a small amount of pressure fluid into the motor, thus causing the reciprocation of the working piston therein. The reversal of the piston stroke will cause the longitudinal vibratory motion of the drilling motor, which will be transmitted to the screw 20 by the lug 22. Referring to Figs. 11 and 12, it will be seen that a small clearance exists between the threads of the screw 20 and the threads of the nut 26, permitting thereby a slight relative longitudinal movement of the screw 2% with the nut 26. The longitudinal vibratory motion imparted to the screw 2!), will repeatedly cause the instantaneous disengagement and engagement of the threads of the screw with the corresponding threads of the nut, thus materially reducing the friction between the threads, and permitting the rotation and longitudinal movement of the screw The longitudinal movement of the screw is transmitted to the drilling motor through the lug 22, thus feeding the motor toward the right.

In the actual drilling operation, when the cutting tool is fed against the work, and the piston within the drilling motor is adapted to deliver its blows to the cutting tool, it is found that considerable recoil is transmitted to the drilling motor and to the feeding mechanism. If the screw 20 was replaced by a simple rod, or by a screw formed with a longer lead angle, the pressure fluid admitted on the feed piston would not be sufiicient to resist the recoil imparted thereto, permitting thereby the drilling motor to be driven away from the work. Furthermore, if the drill assembly was positioned for vertical drilling, it would be impossible to retain the drilling motor on the upper end portion of the feed tube, Without admitting sufficient pressure fluid on the feed piston to overcome the weight of the drilling motor.

With the present construction, since the threads of the screw are formed of a relatively sharp lead single as previously explained, the recoil of the drilling motor is materially prevented by the engagement of the other face of the screw threads 2i) with the corresponding face of the threads of the nut 26 (see Fig. 11). When the drill assembly is positioned for vertical drilling, the drilling motor will remain into the position occupied at the time the pressure fluid is shut off from the motor, by a simple frictional engage- P ment of the threads of the screw 26 with the threads of the nut 26, and irrespective of the weight of the drilling motor not being overcome by pressure fluid which usually would have to be admitted on the feed piston l6.

During the rearward movement of the drilling motor, pressure fluid previously admitted into the front end portion of the feed tube I t, may exhaust therefrom via the port 36, throttle valve groove 45 and vent port 45. When it is desired to feed the drilling motor rearwardly, the throttle Valve 39 may be positioned as illustrated in Fig. 8. In this instance, the pressure fluid is admitted from the valve bore 62, into the front end portion of the feed tube M, through the valve port 43, and port 46, thus admitting pressure on the front side of the piston E5 to move the latter rearwardly or toward the left. The rearward motion of the piston I6 is transmitted to the drilling motor l8 through the feed screw 26, in the manner previously described in connection 4 with the forward movement of the motor. The vibrations resulting from the reciprocation of the piston within the drilling motor transmitted to the feed screw .28 is suflicient to reduce the frictional engagement of the screw with the nut 2'i, thus permitting the rotation of the screw and consequently its longitudinal or feeding movement.

During the rearward motion of the piston l6, pressure fluid previously admitted into the rear end portion of the feed tube H3, is free to exhaust therefrom through the passage 47, valve groove 44 and vent port 35. It will be seen that the vent port 45 is common to both the front and rear end portions of the feed tube. This vent port opens under the throttle valve handle 59, thus protecting the operator from the exhausting pressure fluid.

When it is desired to pack the screw 28, for preventing the escape of the pressure fluid admitted on the feed piston 16 through the port 46, to escape between the screw and the nut 26, the plug 36 with its appurtenant parts, is removed from the nut to permit the introduction of the 7 packing material into the annular groove 28 and bore 29. Subsequently the plug 39 is screwed into the bore 29, thus compressing the packing ma- When the packing material is sumciently com- 7 pressed into the groove 28 and bore 29, the packing material will be forced into the bore 3| of the plug 36, thus forcing the plunger or indicator 33 out of the plug 36 against the tension of the compression spring 35 as illustrated in Fig. 7. The spring 35 is designed in such a manner that when it is fully compressed, the compression of the packing material is at a stage best suitable for its purpose. The indicator or plunger 33 protruding from the bushing 39, will indicate to the Operator the condition of the packing material within the groove 28. When the compression of the packing material decreases within the groove due to particles thereof being carried away by the screw 2! the spring 35 acting on the plunger head 32, will force the latter inwardly, tending thereby to maintain an even compression of the packing irrespective of the dissipation of the latter resulting from its frictional engagement with the screw 26. When the indicator is finally located flush with the end wall of the bushing 39, as shown in Fig. 6, the operator will notice that the plug 39 must be tightened to assure an efiicient compression of the packing. If the plug 30 is at the extreme end of its travel, it must be removed and supplemental packing material be inserted into the bore 29. By this simple construction, the operator may take notice of the condition of the packing within the groove 28, without necessitating the entire removal of the nut 26.

Although the foregoing description is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or confining and it is to be further understood that various rearrangements of parts and modification of structural detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

1. The combination with a drilling motor having a hammer reciprocable therein, of a feeding mechanism therefor including a feed tube, a fluid actuated feeding element reciprocable within said feed tube, a member associated with said feeding element and said motor for transmitting the reciprocation of the former to the latter, and interengaging means on said member and within said feed tube for normally preventing the reciprocation of said feeding element, said means being responsive to the vibratory motion resulting from the reciprocation of said hammer for permitting the reciprocation of said feeding element.

2. The combination with a drilling motor having a hammer reciprocable therein, of a feeding mechanism therefor including a feed tube, a pressure fluid actuated feeding element reciprocable Within said feed tube, a member associated with said feeding element and said motor for transmitting the reciprocation of the former to the latter, and means on said member and within said feed tube capable of frictional inter-engagement for preventing the normal reciprocation of said feeding element, the frictional resistance resulting from said engagement being responsive to the action of the pressure fluid admitted on said feeding element, said means being responsive to the vibratory motion resulting from the reciprocation of said hammer for reducing said frictional resistance, permitting thereby the reciprocation of said feeding element.

3. The combination with a drilling motor hav-- ing a hammer reciprocable therein, of feeding mechanism therefor including a feed tube, a fluid actuated feeding element reciprocable within said feed tube, a member associated with said feed-' ing element and said motor for transmitting the reciprocation of the former to the latter, a stationary bushing within said feed tube through which said member may move, and means on said member and within said bushing capable of forcible intergagement for preventing the reciprocation of said feeding element, said member being responsive to the vibratory motion resulting from the reciprocation of said hammer to cause the interengagement of said means in a manner permitting the reciprocation of said feeding element.

i. The combination with a drilling motor having a hammer reciprocable therein, of a feeding mechanism therefor comprising a feed tube, a fluid actuated feeding element reciprocable within said feed tube, a rotatable member associated with said feeding element and said motor for transmitting the reciprocation of the former to the latter, a stationary bushing within said feed tube through which said member may pass, means on said member and within said bushing engageable with each other in a manner for preventing the rotation of said member and consequently preventing the reciprocation of said feeding element, said member being responsive to the vibratory motion resulting from the reciprocation of said hammer to cause the engagement of said means in another manner causing the rotation of said member responsive to the reciprocation of said feeding element.

5. The combination with a drilling motor having a hammer reciprocable therein, of a feeding mechanism therefor including a casing, a feeding element reciprocable therein, a member associated with said feeding element and said motor for transmitting the reciprocation of the former to the latter, a stationary element associated within said member, means on said member and within said stationary element engageable with each other in a manner preventing the reciprocation of said feeding element irrespective of the relative position of said member with said casing, said member being responsive to the vibratory motion resulting from the reciprocation of said hammer to cause the engagement of said means in another manner permitting the reciprocation of said feeding element.

6. The combination with a drilling motor having a piston reciprocable therein, a frame on which said motor is capable of longitudinal movement, a feeding device associated with said motor capable of imparting longitudinal movement thereto relative to said frame, and of a mechanism comprising members capable of interengagement in a manner preventing the longitudinal movement of said motor relative to said frame, said members being responsive to the vibratory motion resulting from the reciprocation of said piston to cause their interengagement in a manner permitting the relative longitudinal movement of said motor relative to said frame.

7. The combination with a drilling motor having a hammer reciprocable therein, of a carriage therefor comprising a frame on which said motor is capable of longitudinal movement, and of a mechanism for causing or preventing the longitudinal movement of said motor, said mechanism including a casing having a pressure fluid actuable feeding element reciprocable therein, a member associated with said feeding element and said motor for transmitting the reciprocation of the former to the latter, a stationary element associated with said member, means on said member and within said stationary element engageable with each other, said member being subjected to the action of the pressure fluid on said feeding element to cause the engagement of said means in a manner preventing the reciprocation of said feeding element and to the vibratory movement resulting from the reciprocation of said hammer to permit the reciprocation of said feeding element.

8. The combination with a drilling motor having a piston reciprocable therein, a frame on which said motor is capable of longitudinal movement, and of a mechanism adapted to automatically prevent any substantial longitudinal movement of said motor relative to said frame during the inoperation of said piston, said mechanism being rendered inoperative by the vibratory motion imparted thereto resulting from the reciprocation of said piston. 

